2 Answers
2

Benefit: You gain a +2 feat bonus to Stealth checks. Whenever you roll a result you dislike on a Stealth check and you are within 5 squares of an ally that also has this feat, you can reroll the Stealth check with a +1 bonus for each such ally, to a maximum of +5. You can then use the best result

First sentence is very clear. You gain +2 to stealth checks. Period. Just like skill focus.

Second sentence "roll you dislike" is normally used to give a reroll that doesn't stack, for example "Time Link Armor"

Power (Daily): No Action. Trigger: You roll initiative and dislike the result. Effect: You reroll initiative but must use the second result.

In this case, they replaced second with best.
The second bonus is untyped, and therefore offers up to a +5 with 5 qualifying allies around you, for a total of +2 feat and +5 untyped. Maximum total bonus of +7.

The reason for this is that if the party achieves that bonus they are unambigiously shouting at the GM "We want stealthy skill challenges!" and sacrificing a feat for that.

For more details on how bonuses work and their typing, look at pages 27 and 28 of the rules compendium or here.